Current growth rates for the digital magnetic recording data storage industry show an increase in recording densities of 60% per year. To continue on this growth rate curve, the recording industry is being forced to make a number of significant changes in the design of the magnetic recording device. Digital magnetic recording devices for data storage generally comprise a thin film magnetic recording disk and a head or transducer which is moved along or above the surface of the rotating disk to read and write information on the disk. Advanced high areal density, thin film magnetic recording disks comprise a rigid substrate preferably having a dual zone textured surface, a magnetic layer such as a cobalt-based metal alloy, a protective amorphous carbon layer and a lubricant layer, such as a perfluoropolyether disposed on the carbon overcoat. The dual zone texture of the disk substrate is made up of a highly polished surface over the area of the disk used for reading and writing data, and a textured surface over the area of the disk used for landing the head when the recording device is not in use. The highly polished surface of the "data zone" functions to: a) minimize interactions between the surface of the disk and the head and b) reduce the number of errors encountered during reading and writing operations. No data is stored in the textured "landing zone" and its presence is desired to eliminate stiction upon file start-up. Stiction is the tendency of a landed stationary magnetic recording head to resist movement, e.g., translational movement along the surface of the disk. High stiction can lead to mechanical failure of the head or disk.
The transducer is attached to a carrier or slider having an air bearing surface which is supported during operation adjacent the data surface of the disk by a cushion of air generated by the rotating disk. Since recording density depends exponentially on the separation distance between the recording element of the head and the magnetic layer of the disk, lower fly heights are needed for high areal density recording, and a head utilizing a negative air bearing, such as described in U.S. Pat. No. 4,894,740, may be employed to achieve high areal density. However, lower fly heights can cause an increase in the interaction of the head with the disk during normal flying.
The recording device also comprises a positioning actuator connected to the carrier for moving the head to the desired location on the disk during reading or writing operations.
Gitis PCT application US9309460, published Apr. 14, 1994, teaches that during operation, the head and disk are exposed to particulate contaminates such as dust and carbon particles fractured from the protective carbon layer of the disk by head/disk contact. These particles tend to build up on the slider and may eventually lead to head crash during operation of the recording device. Gitis claims vapor depositing low surface energy polymers on the wear pad of the slider of contact recording devices and a vertical side, to minimize particle build up on the slider.
Conventional non contact magnetic recording devices are operated at a rotational speed of about 3600 RPM to about 5400 RPM and at fly height of 80 to 100 nm. It has been discovered that stiction problems are encountered when high areal density recording devices are operated continuously at higher speeds, e.g., 7200 and lower fly heights. However, it is desired to reduce the data access time for high areal density recording by increasing the rotational speed of the disk without encountering the stiction problem. There still is a need in the art for a high areal density magnetic recording device which can operate at higher rotational speeds without stiction.
It is an object of the present invention to provide an improved high areal density, non contact magnetic recording device which operates at a higher rotational speed without a stiction problem.
Other objects and advantages will be apparent from the following disclosure.